Supporters and family members of Mumtaz Qadri sit near his body after his execution in Rawalpindi, Pakistan, on February 29. Qadri was hanged for murdering a provincial governor in 2011 after the official called for reform of the country's strict blasphemy laws.

Amnesty International says the number of confirmed executions across the world surged to its highest level in more than two decades in 2015, fueled by the rising use of capital punishment in Iran, Pakistan, and Saudi Arabia.

In a report released on April 6, the London-based rights group said at least 1,634 executions were recorded worldwide during 2015, a more than 50 percent rise compared to the 1,061 executions recorded the previous year.

The vast majority of these confirmed death sentences were carried out in Iran, Pakistan, and Saudi Arabia, whose combined total constitutes 89 percent of all executions recorded in the Amnesty report.

“Iran, Pakistan, and Saudi Arabia have all put people to death at unprecedented levels, often after grossly unfair trials. This slaughter must end," Salil Shetty, Amnesty International’s secretary-general, said in a statement.

Shetty called the rise in executions worldwide "profoundly disturbing."

"Not for the last 25 years have so many people been put to death by states around the world. In 2015, governments continued relentlessly to deprive people of their lives on the false premise that the death penalty would make us safer,” he said.

The actual number of executions is likely higher. The report did not include China, which Amnesty describes as “the world’s top executioner,” because statistics on the use of the death penalty there are classified as a state secret.

"China’s executions remain in the thousands annually," the report says, adding that this number may be on the decline since China’s Supreme People’s Court began reviewing the implementation of capital punishment in 2007.

Despite the spike in the number of executions, Amnesty said there were positive developments in the drive to abolish the death penalty, which the rights watchdog opposes “in all cases without exception.”

Oluwatosin Popoola, a death penalty expert at Amnesty, told RFE/RL that "2015 was a year of extremes."

"Although there were many setbacks in the fight for abolition, some positive developments offered hope,” he said. “Congo Republic, Fiji, Madagascar, and Surinam abolished the death penalty for all crimes."

Amnesty noted that Mongolia is also set to abolish the death penalty later this year. For the first time ever, it said, a majority of countries in the world -- 102 -- have now abolished the death penalty.

"In total, 140 states across the globe are abolitionist in law or practice," it said.

Popoola added that the death penalty "is becoming a thing of the past in the Americas region, where executions in the U.S. reached their lowest level in 24 years."

‘State-Sanctioned Killing Spree’

Iran ranked second after China in 2015, putting at least 977 people to death, primarily for drug-related crimes, according to the report. That figure is up from 743 the previous year and includes four people who were under 18 years old when they committed crimes they were ultimately convicted of, Amnesty said.

Popoola told RFE/RL that the rise in recorded executions in Iran could be attributed to greater access for human rights monitors in the Islamic republic.

"Some executions take place in secret, so it is very possible that human rights monitors are now in a better position to record executions in the country," he said.

Pakistan, meanwhile, "continued the state-sanctioned killing spree it embarked on when it lifted a moratorium on civilian executions in December 2014," Amnesty said in its report.

Amnesty said Pakistani authorities put more than 320 people to death in 2015, the highest number ever recorded by the rights group for the country.

In Saudi Arabia, it said, at least 158 people were executed in 2015, up 76 percent from the previous year. Most of these individuals were beheaded, the report said, though "authorities also used firing squads and sometimes displayed executed bodies in public."

Popoola said this rise could be connected to an effort by Saudi authorities "to appear tough on crime."

There were no executions in Europe or Central Asia in 2015, Amnesty said in the new report. Belarus is the only country in the region that currently uses the death penalty, and it did not execute anyone in 2015, the report said.

Amnesty noted, however, that Belarus handed down at least two new death sentences last year. The rights group criticized Minsk in its previous annual report for putting three people to death in 2015.

Those executions were marked by secrecy, and family members and lawyers were informed only after they were carried out, Amnesty said.

Kazakhstan, Russia, and Tajikistan continued to observe official moratoriums on the use of the death penalty in 2015, Amnesty said in its latest report.

The report said that in the majority of countries where people were sentenced to death or executed in 2015, “the death penalty was imposed after proceedings that did not meet international fair trial standards.”

In some cases, it added, convictions were based on forced “confessions” that may have been obtained through torture or other abuses.